1. Field of the Invention
The present invention relates to a light scanning apparatus for an electrophotographic image forming apparatus. More particularly, the present invention relates to an optical shutter which adjusts the amount of light transmitted using an electro-wetting phenomenon and an optical scanning apparatus employing the same.
2. Description of the Related Art
In general, electrophotographic image forming apparatuses, e.g., photocopiers, laser printers, and facsimiles, produce desired images by forming a latent electrostatic image on a photosensitive medium, e.g., a photoreceptor drum or a photoreceptor belt, developing the latent electrostatic image with a developer of a predetermined color, and transferring the developed image to paper. The image forming apparatus includes a laser scanning unit (LSU) forming a latent electrostatic image corresponding to a desired image by scanning light onto a surface of the photosensitive medium.
FIG. 1 shows a configuration of a conventional light scanning apparatus for a conventional electrophotographic image forming apparatus.
Referring to FIG. 1, a conventional light scanning apparatus 10 includes a laser diode (LD) 11 as a light source for emitting a laser beam, a polygon mirror 12 scanning the laser beam emitted from the laser diode 11, a focusing lens 13 focusing the laser beam reflected by the polygon mirror 12, and a mirror 14 reflecting the laser beam passing through the focusing lens 13 to form an image at a point on a surface of a photoreceptor drum 20 that is an image forming surface.
When the light scanning apparatus 10 scans the laser beam onto the surface of the photoreceptor drum 20 that is charged to a predetermined electric potential, electric charges in an area where the laser beam is scanned are lost. Thus, a latent electrostatic image having a different electric potential from that of other areas is formed where the laser beam is scanned. Since toner supplied by a toner supply roller 30 is selectively attached to the latent electrostatic image by an electrostatic force, the latent electrostatic image is developed into a desired image. The image developed on the surface of the photoreceptor drum 20 is transferred to a print paper P and then fused on the print paper P by a fusing apparatus (not shown).
Since the conventional light scanning apparatus 10 discussed above includes an optical system having a complicated structure to scan a laser beam, the volume of the apparatus and manufacturing costs thereof are large. Also, since the conventional light scanning apparatus 10 scans the laser beam by rotating the polygon mirror 12 using a motor (not shown), there is a limit on how fast a scanning time can be realized, thus limiting increases in printing speed.
One proposed solution to these limitations includes forming a latent electrostatic image on a surface of a photoreceptor drum by adjusting transmissivity of light using a micro-shutter array using a liquid crystal instead of the conventional light scanning apparatus. However, since a polarization panel is used as the micro-shutter for the liquid crystal, the transmissivity of light decreases, thus increasing power consumption of a light source.
Another proposed solution includes an optical shutter employing reflection from air bubbles generated in a light absorbing liquid. However, since the optical shutter requires a heater to generate the air bubbles, manufacturing the optical shutter is difficult and power consumption increases.